The hub model

The hub is the model that has traditionally been used with CICS® dynamic transaction routing.

A routing program running in a TOR routes transactions between several AORs. Usually, the AORs (unless they are AOR/TORs) do no dynamic routing. Figure 1 shows a hub routing model.
Figure 1. Dynamic routing using a hub routing model. One routing region (the TOR) selects between several target regions.
A terminal-owning region (TOR) is connected to four application-owning regions (AORs). A dynamic routing program runs in the TOR and balances transaction requests across the AORs. The TOR is both the requesting region and the routing region. Each of the AORs is a possible target region.
The hub model applies to the routing of:
  • Transactions started from terminals.
  • Transactions started by terminal-related START commands.
  • Program-link requests received from outside CICS. (The receiving region acts as a hub or TOR because it routes the requests among a set of back-end server regions.)
  • Bridge 3270 requests.

The hub model is a hierarchical system; routing is controlled by one region (the TOR). Normally a routing program runs only in the TOR.